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ISC Class XII Board Specimen 2012 : Biotechnology Paper 2

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ISC 12th
Indian School Certificate Examination (ISC), New Delhi

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ISC SPECIMEN QUESTION PAPER FOR 2012 EXAMINATION BIOTECHNOLOGY Paper 2 (Practical) (Three hours) (Candidates are allowed additional 15 minutes for only reading the paper. They must NOT start writing during this time) ______________________________________________________________________________ This paper comprises two sections Section A and Section B. Attempt Question 1 (compulsory) and any two other questions from Section A. Section B is compulsory. The intended marks for questions or parts of questions are given in brackets [ ]. ______________________________________________________________________________ SECTION A Question 1 (Compulsory) (a) You are provided with two stock solutions 1% coconut milk; 1% Sucrose solution and 1 gm of agarose powder. Prepare 100 ml of tissue culture media in a 250 ml flask using the given composition: [10 ml coconut milk + 10 ml sucrose solution + 1% agarose powder and raise the volume to 100 ml using distilled water]. Adjust the media at a pH 6.8 using a pH meter or a pH paper. Sterilize the media using an autoclave. Pour about 4ml of the media in two test tubes to prepare a slant. Answer the questions that follow: (i) What is the role of sucrose and agarose in the given media? (ii) Name the kind of media prepared above. (iii) Explain the principle on which an autoclave works. (iv) What is the purpose of preparing a slant? [1] [1] [1] [1] (b) Perform the experiment described below and answer the questions that follow: Take a ripe mashed banana (about 2 piece) into a beaker and add 30 ml of extraction fluid (E.F) provided to you. Incubate the beaker at 60 degrees C for 15 minutes. Stir gently with a glass rod. Filter 5 ml of the cooled content into a test tube and add 5 ml of cold 90 % alcohol to it. Allow the test tube to stand for 10 minutes. (i) What do you observe in the test tube after 10 minutes? (ii) Give two uses of genomic DNA in molecular biology experiments. (iii) Name a major contaminant found in the above sample. (iv) Name two equipments used for quantitative estimation of DNA. [1] [1] [1] [1] ISC Specimen Question Paper - 2012 Question 2 You are provided with a culture of bacteria isolated from curd. Proceed as follows: Pick up a bacterial colony with a toothpick or an inoculation loop and spread it to a glass slide. Add two drops of crystal violet solution (1%) and gently warm it on a hot plate at 40 degrees C until it becomes dry. Wash the smear with water to remove excess stain. Next, stain the slide with about 2ml of iodine solution for 1 minute. Wash the smear with acetone. Now counterstain the smear with saffranin solution (0.5%) for 1 minute. Again wash the smear with water and observe the slide under the microscope. Answer the questions that follow: (i) Write your observation when the slide is placed under the microscope. [1] (ii) Identify the technique used above and mention its use in the laboratory. [2] (iii) Explain the principle on which this technique is based. [2] (iv) Name the bacteria present in the curd. [1] Question 3 A milk sample for the isolation of proteins has been provided to you. Take 25 ml of the sample in a 50 ml flask and proceed as follows: First warm the sample in a water-bath set at 35 C. Note the pH of the milk sample using a pH meter or a pH paper. Next add 0.4 N HCl using a drop-wise until the protein starts coagulating. Note the pH at which at which maximum separation of protein takes place. Filter the solution through a thin muslin cloth to separate out the protein. Show the protein isolated by you to the visiting examiner. (a) (i) Report the initial pH of the milk sample. [1] (ii) Report the pH at which the protein gets coagulated. [1] (b) Name the protein and carbohydrate present in the above sample. [1] (c) Explain the basic principle involved in the above isolation. [2] (d) How can you calculate the net amount of protein that you have isolated? [1] ISC Specimen Question Paper - 2012 Question 4 Identify the instruments/ photographs of the instruments (1 4) commonly used in a biotechnology laboratory. Write: (a) The names of the instruments. [2] (b) One important structural feature of the instrument [2] (c) Specific uses of the instrument [2] SECTION B Question 5 (a) Show your Project Work / Assignment to the Visiting Examiner for assessment. [7] (b) Submit your Practical File to the Visiting Examiner for assessment. [3] ISC Specimen Question Paper - 2012

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